RESEARCH SEMINAR. 25! 



thoroughly as possible. Some of the poisons used were copper 

 sulphate, silver nitrate, mercuric chloride, citric acid, resorcin, 

 phenol, thymol, etc. The effects could not be due to the action 

 of the insoluble particles on the ions of the poisons which do not 

 dissociate. The variety of insoluble substances used would indi- 

 cate that the effects were not due to the slight solubility which 

 some of the particles possess. Since no othei suggestion pre- 

 sents itself, perhaps the theory of " adsorption " offers the best 

 explanation to the problem. 



August 12. Artificial Sea Water. By RODNEY H. TRUE. 



The experiments now in progress at the United States Fish 

 Commission in connection with the attempts to make artificial sea 

 water capable of sustaining marine life were discussed. Two 

 sorts of solutions were compounded, one a synthetic, prepared by 

 adding to distilled water the required salts in quantities indicated 

 by analysis. The second solution was obtained by dissolving in 

 distilled water a complete sea salt obtained by evaporating sea 

 water to dryness over steam. The importance of the presence of 

 the full amount of calcium was pointed out and the utility of charg- 

 ing the solutions with carbon dioxide gas was noted. The report 

 of the results thus far obtained with the marine plants and animals 

 indicated that the synthetic solutions are less satisfactory than 

 those obtained from evaporated sea salt. The hope was ex- 

 pressed that the latter might be to a considerable degree satisfac- 

 tory for the demands in this direction, but the fact that experi- 

 ments thus far have covered only two summer sessions w T as cited 

 as ground for a cautious interpretation of these results. 



3. BOTANICAL LECTURES AND SEMINARS IN 1904. 



July 12, Dr. George T. Moore: " Botanical Work at Several 

 Botanical Laboratories in Holland, Scandinavia and Russia." 



July 13, Dr. George T. Moore: "The Physiological Methods 

 of Purifying Water Supplies." 



July 15. Mr. Mintin A. Chrysler: " Regeneration in Plants as 

 Illustrated by Zamia Floridana." 



July 19, Miss Etoile B. Simons : " Morphological Studies on 

 Sargassum Filipendula." 



